This is technically from my anthro MLP dreamscape although it has that one-shot special episode quality to it. The setting was summertime and the students and facility from the School of Friendship took a summer study/retreat to a nearby mountain resort. Starlight particularly enjoyed it because the lake was very popular with kite-surfing ponies. Soon she made sure to keep her afternoon free for it.
While Trixie Lulamoon might be a fine magician on stage but when it comes to performing tricks on the water Starlight is the master.